Speaking from my experience running the dungeon twice at Gen Con for groups new to the Dungeon Fantasy Roleplaying Game but not to GURPS: It's probably a two-session dungeon for most gamers – three sessions if the group tends to find combat slow-ish in any game because they like to weigh all the options. People tend to need a while to reach area #6 owing to the puzzle-y nature of the earlier areas . . . and due to roleplaying through the adventure intro with the quest-giver!